The island of Pantelleria (Sicily Strait), the type locality for pantellerite, has been the locus of major calderaformingeruptions that culminated, ca. 50 ka ago, in the formation of the Cinque Denti caldera produced by theGreen Tuff eruption. The post-caldera silicic activity since that time has been mostly confined inside the calderaand consists of smaller-energy eruptions represented by more than twenty coalescing pantelleritic centersstructurally controlled by resurgence and trapdoor faulting of the caldera floor. A high-resolution 40Ar/39Arstudy was conducted on key units spanning the recent (post-20 ka) intracaldera activity to better characterizethe present-day status (and forecast the short-term behavior of) the system based on the temporal evolution ofthe latest eruptions. The new 40Ar/39Ar data capture a long-term (N15 ka) decline in eruption frequency with ashift in eruptive pace from 3.5 ka−1 to 0.8 ka−1 associated with a prominent paleosol horizon marking the onlyrecognizable volcanic stasis around 12–14 ka. This shift in extraction frequency occurswithoutmajor changes ineruptive style, and is paralleled by a subtle trend of decreasingmelt differentiation index. We speculate that thisdecline probably occurred (i) without short-term variations in melt production/differentiation rate in a steadystatecompositionally-zoned silicic reservoir progressively tapped deeper through the sequence, and (ii) that itwas possibly modulated by outboard eustatic forcing due to the 140 m sea level rise over the past 21 ka. Theintracaldera system is experiencing a protracted stasis since 7 ka. Coupled with recent geodetic evidence ofdeflation and subsidence of the caldera floor, the system appears today to be on a wane with no temporalevidence for a short-term silicic eruption.
|Numero di pagine||11|
|Rivista||Earth and Planetary Science Letters|
|Stato di pubblicazione||Published - 2011|
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